The teams that are in every year as you say are because they spend and spend big on the ML roster.

The Twins being the exception but what has that gotten for them?

The Rays too small a sample size.

With the exception of the Yankees (and maybe even including the Yankees) those teams spend a LOT on the draft too. The Rays have made it three of the last four years and have done it almost exclusively through the draft. The Rangers have a lot of homegrown talent, the Cardinals as well. Even the Red Sox have a lot of homegrown guys. The only team that seems to build exclusively through free agency is the Yankees.